Presently, with the development of electronic information technology, smart electronic devices such as smart phones, tablets, and laptops are widely spread and expending their range of use; and the appearance of electronic devices is becoming more diverse.
Wherein, using a dual structure to change the appearance of the electronic device is not uncommon in our daily lives. For example, flip phones that mainly comprise a display panel and the operator panel, laptops, hand-held game consoles that comprise an upper screen and a bottom screen, etc.
Currently, when an electronic device with a dual structure needs to achieve the synchronous movement of both structures in the same or opposite direction, biaxial synchronous gears are normally used to connect each body. FIG. 1 illustrates a biaxial synchronous gear system suitable for use with the embodiments of the present invention that relies on the linkage of crossed helical gears to achieve synchronous movement, and may comprise an upper gear, a middle gear and a bottom gear in a same arrangement direction, wherein a slim electronic device must compress the minimum size of the three gears to lessen the height of a dual structure electronic device. Since, in practice, electronic devices require certain strength biaxial synchronous gears based on the quality assurance, achieving a minimum size of the biaxial synchronous gear structure generally becomes a bottleneck in the design of slim and light type multi-structural electronic devices. It is obvious that in the prior art the biaxial synchronous gears are adopted to achieve synchronous movement of each component of an electronic device, but the occupying space is large and the materials are very heavy. Therefore, the prior art cannot solve the technical problem of slim design for electronic devices.
Moreover, for thin electronic devices, the height of an electric device in dual structures may be reduced by compressing the size of the three gears of FIG. 1 to the limit. However, as the biaxial synchronous gear strength depends on the electronic device quality during operation, the size of the biaxial synchronous gears usually constitutes the bottleneck for the structure design of thin electronic devices in the multiple structures. Therefore, as the biaxial synchronous gears in the existing technology are used for synchronous motion of all structure parts in electronic devices, the existence of the intermediate gear leads to a technical problem restricting further thickness reduction of electronic devices in the multiple structures.